Teleportation, a term originally coined by science fiction, refers to a hypothetical technology that can transport objects (or, eventually, people) nearly instantaneously from one location to another without sending the object through the intervening space. Classically, one might approach this problem by attempting to record the states of all the particles constituting the object to be teleported; that information could then be transmitted to a distant receiver and used to reconstitute the object out of raw materials available at the receiver. For many years this approach to teleportation was considered implausible because of quantum mechanical concerns. For instance, a teleportation device must somehow record the precise positions and momenta of all atoms in an object in order to reconstruct the object on the other side. This simultaneous measurement of non-commuting observables is forbidden by the uncertainty principle. A more fundamental problem exists, though, which is evident even in situations where the uncertainty principle is not directly applicable. To illustrate this point, consider the teleportation of a (more…)